Three-dimensional ex vivo angiogenesis system

Abstract

An in vitro tissue angiogenesis and vasculogenesis system is disclosed that allows the outgrowth of microvessels from a three-dimensional tissue fragment implanted in a matrix. The matrix may, for example, be a fibrin- or collagen-based matrix fed by a growth medium, for example, a mixture of tissue culture medium, serum, or a layer of growth medium containing a defined mixture of growth factors. This system, which may be used with human or other mammalian or animal tissues, may be used in assaying tumor angiogenic potential, or in promoting angiogenesis in other tissues, e.g., promoting angiogenesis prior to transplantation of a tissue. The angiogenic potential of a tissue can be determined by measuring the growth of microvessels into the matrix. The three-dimensional structure of the tumor or other tissue is maintained in the matrix, including blood vessels. In another aspect, the method allows for the proliferation of a tissue specimen, thus increasing the mass of cells available for subsequent transplant; and the method also provides for the proliferation of blood vessels from the tissue mass, thus enhancing the chance of successful engraftment.

1 - 23 . (canceled)  
     
     
         24 . A method for growing a tissue ex vivo and subsequently transplanting the tissue into a host in need of such a transplant, said method comprising the steps of: 
 (a) embedding a three-dimensional mammalian tissue sample in a matrix, wherein the tissue sample has at least one cut surface exposing blood vessels;    (b) supplying to the embedded tissue sample a medium that supports the growth of the tissue sample;    (c) incubating the embedded tissue sample in the medium for a time sufficient to allow angiogenic vessels to grow into the matrix surrounding the tissue sample; and to allow the number of cells in the tissue to proliferate, so that the tissue's suitability for transplant is improved; and    (d) subsequently transplanting the incubated embedded tissue sample with angiogenic vessels into a host in need of such a transplant.    
     
     
         25 . (canceled)  
     
     
         26 . A method as recited in  claim 26 , wherein said incubating step is conducted for a time sufficient for the mass of the tissue to increase by at least about 25%.  
     
     
         27 - 37 . (canceled)  
     
     
         38 . A method as recited in  claim 24 , wherein the medium comprises serum.  
     
     
         39 . A method as recited in  claim 24 , wherein the medium comprises an angiogenesis-enhancing factor.  
     
     
         40 . A method as recited in  claim 39 , wherein the angiogenesis-enhancing factor is selected from the group consisting of platelet-derived growth factor, vascular endothelial growth factor, epidermal growth factor, fibroblast growth factor, and transforming growth factor β.  
     
     
         41 . A method as recited in  claim 24 , wherein the matrix comprises fibrin.  
     
     
         42 . A method as recited in  claim 24 , wherein the matrix comprises collagen.  
     
     
         43 . A method as recited in  claim 24 , wherein the matrix comprises gelatin.  
     
     
         44 . A method as recited in  claim 24 , wherein the matrix comprises agarose, agar, alginate, or silica gel.  
     
     
         45 . A method as recited in  claim 24 , wherein the matrix comprises Matrigel™ matrix.  
     
     
         46 . A method as recited in  claim 24 , wherein the tissue sample is selected from the group consisting of skin tissue, parathyroid tissue, thyroid tissue, pituitary tissue, adrenal tissue, pancreas tissue, cardiac muscle tissue, skeletal muscle tissue, retina tissue, kidney tissue, and liver tissue.  
     
     
         47 . A method as recited in  claim 24 , wherein the three-dimensional tissue sample comprises multiple layers of cells comprising blood vessels, supportive stromal elements, neural cells, and endothelial cells; wherein the architecture of the tissue sample is substantially intact and has not been disrupted as compared to that of comparable tissue in vivo; and wherein the three-dimensional tissue sample does not consist of an isolated artery or an isolated vein.